The Duke and Duchess of Cambridge were walking arm in arm on a secluded beach near their Mustique villa, when the pictures were taken.

Although the island is privately owned and paparazzi are banned, it seems eagle-eyed snappers managed to catch a handful of long-lens shots of William and Kate from a boat out at sea, as they relaxed on the private beach – including pictures of Kate Middleton’s baby bump.

The royal household is said to be ‘disappointed’ by the private photo leak.

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A spokesman for the couple at St James’s Palace said: ‘We are disappointed that photographs of the Duke and Duchess on a private holiday look likely to be published overseas.

‘This is a clear breach of the couple’s right to privacy.’

An insider told the Mirror that Prince William and Kate Middleton have been told about the photos, and were ‘furious’ when they heard the news.

‘The Duke and Duchess are obviously furious about this,’ the source said.

‘Yet again they have been unable to even have one week of holiday without, apparently, images being taken against their will.

‘This is all the more worrying at a time when the Duchess is pregnant and obviously raises their concerns about what sort of family life their children will have if this kind of thing continues.’

This is not the first time private pictures of Prince William and Kate Middleton have surfaced.

Last year the royal couple were said to be ‘saddened’ after photos of Kate Middleton sunbathing topless at a private chateau in France were published by French Closer magazine.

Earlier in the year, Australian monthly title Woman’s Day made the controversial decision to publish the ‘world exclusive’ photos of the Duke and Duchess of Cambridge, taken on the beach during their private honeymoon in the Seychelles last May.

WATCH: Kate Middleton’s most iconic style moments

What do you think of news pictures of pregnant Kate Middleton in a bikini will be published by an Italian magazine? Should the Kate Middleton baby bump photos be private? Let us know in the comments box below…

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